Fire alarms



June 6,1961 REWARDS Em 3,324,464

FIRE ALARMS Filed May 11, 1964 FIGJI- INVENTORS: ROBERT EDWARDS WILLIAM A. WHEATLEY THEIR ATTORN EYS.

United States Patent FIRE ALARMS Robert Edwards, Westfield, and William A. Wheatley, Middletown, N.J., assignors to Electronic Assistance Corporation, Red Bank, NJ., a corporation of New York Filed May 11, 1964, Ser. No. 366,422 4 Claims. (Cl. 340-2271) This invention relates to improvements in fire alarms of the type usable in residences, business establishments and the like, and which sound an alarm in response to an increased temperature caused by a fire.

A great many different types of fire alarms have been devised heretofore which operate on the general principle that a temperature of a certain magnitude causes a fusible member to melt or a thermostatic element to be actuated to initiate operation of a bell, buzzer, siren, whistle or the like. In the prior alarm systems, the thermostatic or fusible member, when heated sufiiciently may either close an electrical circuit connected with the householder building wiring circuits, actuate a battery or release gas under pressure to energize the signalling or sounding device. The type of alarm which closes an electrical circuit requires a connection with the building circuit, and thus limits the location of the fire alarm device, requires rewiring of the building or has a dangling connecting cord which is unsightly and which can very readily be disconnected inadvertently or even damaged before the alarm is energized.

Fire alarms in which a battery is activated by introducing an electrolyte into a battery cell are complicated and expensive to manufacture and not completely foolproof because of danger of leakage of the electrolyte.

In the gas-pressure type of alarm, no external connections are necessary, but if leakage of the gas occurs, the fire alarm is rendered ineffective without indicating to the user thereof that the alarm is defective.

In accordance with the present invention, a completely self-contained fire alarm device is provided which can be hung upon a wall and left there for a long period of time without deterioration and which, if damage should occur to it other than by way of a fire, will indicate that the device is defective or damaged.

More particularly, in accordance with the present invention, a fire alarm is provided which includes the electrodes of a battery and a separate sealed bag-like container formed of a plastic film for storing an electrolyte required for activating the battery to sound an alarm such as a horn, bell, buzzer or the like, the electrolyte being discharged only upon melting or softening of a heat-responsive fusible element. More particularly, when the fire alarm device is subjected to a higher temperature than that normally occurring in the space where it is located, the fusible element melts and releases a spring actuated member which punctures or tears the container of the electrolyte so that the electrolyte is discharged into contact with the battery electrodes, thereby activating the battery to supply energy to an electrical signaling device to give a warning signal.

Inasmuch as a fire alarm of the type embodying the present invention is completely self-contained and is constructed and arranged so that the battery is not activated until the electrolyte is released into contact with the electrodes of the battery, it has an extremely long shelf or nonoperating life, and consequently can be relied upon almost indefinitely.

For a better understanding of the present invention, reference may be had to the accompanying drawings, in which FIGURE 1 is a front elevational view of a typical fire alarm embodying the present invention;

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FIGURE 2 is a view in section taken on line 2-2 of FIGURE 1;

FIGURE 3 is a view in section taken on line 33 of FIGURE 2; and

FIGURE 4 is a plan view of the container for the electrolyte for the battery of the fire alarm.

Fire alarms of the type embodying the invention can be made in many different shapes and sizes. As illustrated in the drawings, one form of alarm includes a dome-like casing 10 having a front grille 11 provided with suitable ornamentation 12 or the like, as may be desired. The grille 11 is disk-like and contains perforations, slots or the like, 13. It may be formed of plastic, metal or the like and is snapped into an aperture 14 in the casing 10, as best shown in FIGURE 2. Grilles 11 of many different designs, colors and ornamental effects may be provided to match the decor of the area where the fire alarm is located.

As shown in FIGURES 2 and 3, the casing 10 includes an outer curved wall 15 and an inner annular wall 16 which merges into and is joined to the outer wall at the front of the casing. The rear edges of the outer wall 15 and the inner wall 16 are sealed by means of an insert ring or disk 17 which may be swaged, cemented or otherwise secured to the walls 15 and 16in liquid-tight relation thereto. Disposed within the inner annular wall and supported thereby, is an electrically actuated horn 18 of the type commonly used in bicycle and small vehicle horns and which has a high pitched penetrating sound. Such horns are provided with adjusting screws 19 by which the pitch and intensity of the sound may be varied.

Mounted below the inner wall 16 is a carbon electrode 20, forming one electrode of a wet cell battery. As shown in FIGURES 2 and 3, the carbon electrode has a strip of insulating plastic 21 wrapped around its mid-portion and the ends of the strip are inserted in and secured in a socket 22 formed integral with the housing 10. The carbon electrode is spaced from the outer wall 15 of the shell and also insulated from all of the rest of the shell. A wire 23 extends from a conducting collar 24 in electrical contact with the electrode 20 to one terminal 25 of the horn 18, the shell of the horn being the other terminal. The wire extends through an insulating grommet 26- which is in liquid-tight relation to a hole 27 formed in the inner wall 16.

In the preferred form of the invention, the casing 10 of the fire alarm also forms an electrode of the battery. To that end, the casing 10 and the ring or disk 17 are castings of a metal, such as Zamak, a well-known zinc casting metal, thereby forming an electrode of a zinc carbon battery.

In the new fire alarm, the electrolyte is contained in a sealed flexible tube 28 which extends around the upper part of the casing 10 between the outer wall 15 and the inner wall 16. As shown in FIGURE 4, the tube 28 may be formed of a film of polypropolyene or polyethylene or other suitable material which is resistant to corrosion or damage by the electrolyte contained therein. The opposite ends of the tube 28 are sealed by means of heatsealed fins 29 and 30 so that the electrolyte is retained therein and will be retained therein unless the tube 28 is punctured. Puncturing occurs in accordance with the present invention. only when the fire alarm is subjected to a predetermined abnormally high temperature in the area in which the fire alarm is placed.

As best shown in FIGURE 3, the inner wall 16 is provided with a pair of flanges 31 and 32 on opposite sides thereof adjacent the opposite ends of the tube 28. Pins 33 and 34 are either fixed to or cast integral with the flanges 31 and 32, respectively, and are adapted to receive spring members 35 and 36 having a coiled central portion and two arms which are normally disposed at about 180 apart. Also mounted in the flanges 31 and 32 are pins 37 and 38 formed of a fusible metal. Thus, the pins may be formed of a tin alloy having a melting point of 150 to 165 -F., more or less, and which at high but not abnormal room temperatures will retain the springs 35 and 36 under tension with the ends of the arms adjacent to each other.

The fire alarm is hung on a wall by means of a nail or hook extending through an opening 39 in a tab 40 extending from the back plate 17. When the temperature of the surrounding atmosphere rises to or above the temperature at which the fusible pins melt, the springs 35 and 36 are released so that arms thereof will swing out through an are as indicated in dotted lines in FIGURE 3 and willtear holes in opposite ends of the tube 28. The electrolyte flows out of the tube into the bottom of the casing and immerses, at least partially, the carbon electrode 20, thereby forming with the casing and the electrode 20 a wet cell battery having a voltage sufiiciently high to actuate the horn 18. It has been found that by the use of a suitable electrolyte in a battery of the type described, an output of about 2.3 volts is obtained very quickly and is sufficient to actuate the horn 18 at high sound intensity and continue to actuate the horn over a period of 45 to 60 minutes, or longer.

A suitable electrolyte for the battery may consist of the following:

CrO (chromic acid) 100 Sulphuric acid (concentrated) 25.5 Water c 100 Copper sulfate 1 all parts being by weight.

If the electrolyte should leak into the casing because of damage to the tube 28, the battery will be activated to sound the horn when the electrolyte rises to the level of the carbon electrode.

While, as indicated above, the casing of the fire alarm may be composed of zinc to form one electrode of the battery, other arrangements are possible. Thus, the casing 10 of the battery may be formed of plastic and it may be provided with a liner or layer of zinc in the bottom portion thereof. In this case, an electrical connection must be made from the zinc electrode to the casing of the horn 18 which forms the second terminal of the horn. In the form of the invention illustrated in the drawing, the horn casing is directly in contact with the zinc inner wall 16 of the casing so that one terminal of the horn is connected to the zinc electrode and the other terminal is connected to the carbon electrode.

It Will be understood that other arrangements of the components of the fire alarm are possible and that the horn may be mounted in one part of a casing while the battery electrodes, fusible pins and electrolyte container may be mounted in another part of the casing, depending 4 upon the appearance sought. Likewise, multipart casings including, for example, a separate horn casing, can be provided, if desired. Accordingly, it will be understood that the form of the invention described herein is illustrative and the invention is limited only as defined in the following claims.

We claim:

1. An alarm comprising a battery having a carbon electrode, an electrical signaling device, a zinc casing for said signaling device forming another electrode of said battery, a container of thin rupturable material in said casing, an electrolyte in said container for activating said battery, means connecting said electrodes to said signaling device and means in said casing responsive to a predetermined temperature for rupturing said container to discharge said electrolyte into contact with said electrodes to supply electrical energy to said signaling device.

2. An alarm comprising a hollow casing, a sleeve in said casing dividing said casing into separate, substantially concentric inner and outer compartments, an electrical signaling device in said inner compartment, a battery having spaced apart electrodes, one of said electrodes forming at least a part of said outer compartment and another electrode being disposed within said outer compartment below said inner compartment and insulated from said one electrode, means connecting said signaling device to said electrodes, a rupturable container in said outer compartment at least partially above said inner compartment, an electrolyte in said container for activating said battery, and a spring having an arm biased toward said container to rupture it, a fusible member engaging said arm to restrain said arm against movement toward said container, said fusible member being responsive to a predetermined temperature for releasing said arm for movement toward said container to rupture said container and discharge said electrolyte into contact with said electrodes and activate said battery and actuate said signaling device.

3. The alarm set forth in claim 2 in which said outer compartment is composed principally of zinc and forms said one electrode and said other electrode comprises a carbon rod.

4. The alarm set forth in claim 2 in which said container is a flexible sealed bag resistant to damage by said electrolyte.

References Cited UNITED STATES PATENTS 3/1917 Firey 136-162.1 6/1961 Collum 340-227 

1. AN ALARM COMPRISING A BATTERY HAVING A CARBON ELECTRODE, AN ELECTRICAL SIGNALING DEVICE, A ZINC CASING FOR SAID SIGNALING DEVICE FORMING ANOTHER ELECTRODE OF SAID BATTERY, A CONTAINER OF THIN RUPTURABLE MATERIAL IN SAID CASING, AN ELECTROLYTE IN SAID CONTAINER FOR ACTIVATING SAID BATTERY, MEANS CONNECTING SAID ELECTRODES TO SAID SIGNALING DEVICE AND MEANS IN SAID CASING RESPONSIVE TO A PREDETERMINED TEMPERATURE FOR RUPTURING SAID CONTAINER TO DISCHARGE SAID ELECTROLYTE INTO CONTACT WITH SAID ELECTRODES TO SUPPLY ELECTRICAL ENERGY TO SAID SIGNALING DEVICE. 